There are essentially two types of dyeing.
The first is semi-permanent dyeing or direct dyeing, which involves dyes capable of giving the hair's natural color a more or less pronounced change.
The dyes used are colored and coloring substances that have a certain affinity for keratin fibers.
It should be noted that this type of dyeing fades out after several washes, which may be an inconvenience.
When it is desired to obtain a coloration that is lighter than the original color of the fibers, it is necessary to use, with the direct dyes, at least one oxidizing agent, under alkaline pH conditions.
However, these conditions of use are not free of consequences on the properties of the treated fibers. Specifically, in the long run, the fibers are more or less degraded and have a tendency to become coarse, dull, brittle and difficult to style.
The second is permanent dyeing or oxidation dyeing. This is performed with oxidation dye precursors, which are colorless or weakly colored compounds, comprising at least one oxidation base optionally combined with at least one coupler. Once mixed with oxidizing products, at the time of use, the precursors give rise to colored compounds and dyes via a process of oxidative condensation.
Given the necessary presence of an oxidizing agent in this type of dyeing, the drawbacks mentioned above also occur in this case.
Moreover, it has been shown that fluorescent dyes may be advantageous in hair dyeing. However, the stability on storage of compositions containing standard fluorescent dyes can be improved.
Moreover, it would also be advantageous to further enhance the wash-fastness and shampoo-fastness of the colorations obtained using these compositions.